Problem 37 - Chemistry Matter and Change

Question

Metals What is the oxidation number of alkaline earth metals in their compounds? Of alkali metals?

Step-by-Step Solution

Answer

The oxidation number of alkaline earth metals in their compounds is \(+2\), and the oxidation number of alkali metals in their compounds is \(+1\).

Step 1: Oxidation Numbers

(A quick review on oxidation numbers) Oxidation numbers are assigned to elements in compounds to indicate the degree of oxidation or reduction. They are used to represent the transfer of electrons in chemical reactions. Here are some general rules for assigning oxidation numbers: 1. The oxidation number of an element in its natural state is 0. 2. The oxidation number of a monatomic ion is equal to its charge. 3. In a compound, the sum of all the oxidation numbers of the atoms is equal to the overall charge of the compound.

Step 2: Alkaline Earth Metals

(Oxidation number in compounds) Alkaline earth metals are found in Group 2 of the periodic table and include Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). In their compounds, alkaline earth metals typically lose two electrons to achieve a stable electron configuration, forming a +2 ion. Therefore, the oxidation number of alkaline earth metals in their compounds is +2.

Step 3: Alkali Metals

(Oxidation number in compounds) Alkali metals are found in Group 1 of the periodic table and include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). In their compounds, alkali metals typically lose one electron to achieve a stable electron configuration, forming a +1 ion. Therefore, the oxidation number of alkali metals in their compounds is +1. In conclusion, the oxidation number of alkaline earth metals in their compounds is \(+2\), while the oxidation number of alkali metals in their compounds is \(+1\).

Key Concepts

alkaline earth metals

Alkaline earth metals are a fascinating group of elements found in Group 2 of the periodic table. This group consists of Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). These metals share some common properties, making them quite similar despite their differences in mass and size.

One of these common properties is that in chemical reactions, alkaline earth metals typically have an oxidation number of +2. This means they lose two electrons to form stable ions with a +2 charge. Losing these two electrons helps them achieve a full outer electron shell, that is typically similar to the stable electron configuration of their nearest noble gas. This makes them highly reactive, especially with halogens and water, though they are less reactive than the group next to them - the alkali metals.

Alkaline earth metals have a shiny metallic appearance and are good conductors of electricity. They are crucial in various applications, such as in the construction industry (Calcium in cement), and in the production of fireworks (Strontium and Barium). Despite their reactivity, they are less reactive than alkali metals, making them slightly more abundant in nature.

alkali metals

Alkali metals are located in Group 1 of the periodic table and include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). These metals are known for being highly reactive and are usually found in nature combined with other elements.

In their compounds, alkali metals typically have an oxidation number of +1. This is because they almost always lose one electron, becoming positively charged with a +1 charge. This electron loss allows them to achieve a stable electron configuration, mimicking the nobility of the nearest noble gas. This ease in losing one electron makes them incredibly reactive, especially with water, producing hydroxides and releasing hydrogen gas.

Due to their high reactivity, alkali metals are usually stored in oil to prevent them from reacting with moisture in the air. They have vital applications in daily life and industry, such as in the manufacture of glass (Sodium) or in rechargeable batteries (Lithium). Being the most reactive metals, they need careful handling, but their utility in various fields makes them indispensable.

periodic table groups

The periodic table is a comprehensive arrangement of the chemical elements, organized by increasing atomic number. It is divided into columns known as groups and rows termed as periods. Each group contains elements that share similar chemical and physical properties.

Groups in the periodic table are distinguished by their vertical columns. For instance, Group 1 houses the alkali metals, while Group 2 is home to alkaline earth metals. These groups are significant as they determine the reactivity of elements and their oxidation states.

The periodic table groups help predict the types of ions elements will form based on their position. For example, elements in Group 1 form +1 ions, and those in Group 2 form +2 ions. These patterns are due to the valence electrons—the electrons in the outermost shell—which decide the chemical interactions.

Understanding the periodic table groups is crucial as they provide insight into elemental behavior. This knowledge aids in the study of chemical reactions, bonding, and the creation of compounds. The organization of the periodic table is a fundamental concept for students delving into the world of chemistry.